1. Field of the Invention
The present invention relates to a method for detecting a contact position where probe pins are first brought into contact with a wafer at the time of an IC test.
2. Description of the Related Art
For the purpose of inspecting an IC at its wafer stage, there has been used an EB (electron beam) test system which inspects a wafer by the use of an electron beam. In this EB test system, probe pins connected to a semiconductor test device (IC tester) are first moved to detect a first touch position where the probe pins are first brought into contact with the wafer. Thereafter, the probe pins are pushed against the wafer by a constant distance from the first touch position so that the probe pins may come into certain contact with the wafer.
According to a prior art method for detecting a contact position in such an EB test system, the first touch position is detected by manually moving the wafer little by little while checking the state of contact between the wafer and probe pins with the semiconductor test device.
Such a prior art method for detecting a contact position will be explained below with reference to a flowchart of FIG. 1.
The operator first uses a semiconductor test device to conduct a contact test to find out whether or not the wafer is in contact with the probe pins (step 31). When the operator determines that the wafer is not in contact with the probe pins in step 31, the operator manually raises the stage upon which the wafer is carried by one pitch (step 32) and again conducts the contact test (step 31). When the contact between the wafer and probe pints is detected, the test processing is terminated (step 32).
However, the aforementioned prior art method is a disadvantageous in that a time necessary for the position detection is long because detection of the first touch position is carried out manually.